There are two types of cholesterol. Too much ‘bad’ cholesterol, the low-density lipoprotein, is linked to coronary heart disease and stroke. By contrast, having too little ‘good’ cholesterol — the high-density lipoprotein (HDL) — is also linked to these conditions. Studies of patients with Tangier disease, who have no HDL circulating in their blood, now shed light on the mechanism of HDL metabolism.
